Soil resources and development of soil information system in Thailand

The soil resources in Thailand was initiated a soil survey task at the national level and produced a soil map at a scale of 1:2,500,000 in 1935 .The soil map legend display only major soil groups with top soil properties. When Land Development Department (LDD) was established in 1963 within the Ministry of National Development (Ministry of Agriculture and Cooperatives now) and soil survey division was also established. From 1979, a soil map of Thailand (scale 1:250,000) was introduced as well as the USDA Soil Classification System (1938) to be adapted for soil survey work in Thailand. Soil Taxonomy was later used for the National Classification System. Soil map (scale 1:1,000,000 at the national level, 1:500,000 at the regional level, 1:100,000 at the provincial level and 1:50,000 at the project level) were published and disseminated to users. In 1989, LDD introduced soil series group maps (scale 1:50,000) of all provinces. The methodology was grouping the 300 soil series into 62 soil series groups mainly considered the similarities of soil properties as well as the soil environment. The main objectives of grouping the soil series into 62 soil series groups were for suitable land management as well as the transfer of soil management technologies to other areas. In 1996 LDD had developed application programs in response to the need of GIS less skilled end users and institutes concern. The application programs mostly under ArcView environment such as SoilView (soil database application software), ThaiPedon (typical soil series profiles software), ErosView (soil erosion software), ConPlan (land development village soil and water conservation planning software) and AgZon (economic crops zoning software). In 2001 to following the Soil Taxonomy (1999) a new draft of the generalized soil map of Thailand at a scale of 1:1,200,000 was revised. The legend of this map basically included the soil map unit being classified at the great group level. In order to summarize the soil characteristics of each map unit the soil of the same soil moisture regime are group together and described. The most extensive soil moisture regime are the ustic and udic moisture regimes as well as the soil with aquic conditions. Soils formed under these moisture regimes show significant differences in their morphology and behavior. For establishment of an appropriate regional SIS for sustainable crops production in ASPAC, soil data from Thailand can advantage well.